In a rolling mill, work roll shafts are rotatably supported by bearings. Once bearings have been fitted to a work roll shaft, they must be located axially and the axial location must be able to withstand the anticipated axial thrust forces from the shaft.
As shown in FIG. 1, a conventional arrangement for axial location of a bearing 1 on a work roll shaft 2 having a longitudinal axis X in a circumferential rectangular groove 3 which is cut into the shaft, with radii in the corners, and into which a split ring 4 is inserted. The two halves of the split ring 4 are connected together, for example by a pivot at one side and by a bolt at the other side, so that the assembled ring is slipped over the shaft 2 and then the bolt is inserted to hold the split ring 4 together. A bearing retaining sleeve 5 having a threaded end 5a is tightened against the side of the split ring 4 by a threaded collar 6, forcing the split ring 4 axially against the outer face of the groove 3, while simultaneously holding the inner race of the axial bearing 1 against an abutment face 7, which may be a spacer or a neck ring of the shaft 2. This securely locates the bearing 1 onto the roll shaft 2.
One unintended consequence of this arrangement is to weaken the work roll shaft. Not only is the shaft cross-section reduced, but also the shape of the profile gives rise to stress concentrations. This can lead to premature failure due to fatigue. As the market moves toward wider rolling mills with correspondingly greater torque values, this is a growing problem.